This invention relates generally to gas turbine engines, and more specifically to methods and apparatus for operating gas turbine engines.
At least one gas turbine engine includes in serial flow arrangement, a low-pressure compressor, a high-pressure compressor for compressing air channeled from the low-pressure compressor, a combustor in which fuel is mixed with the compressed air and ignited to form a high temperature gas stream, and a high-pressure turbine coupled to the high-pressure compressor. The high-pressure compressor, combustor and high-pressure turbine are sometimes collectively referred to as the core engine. Moreover, at least one known gas turbine engine includes an intermediate turbine coupled to the low-pressure compressor, and a free or power turbine that is driven by gases discharged from the high and intermediate pressure turbines.
During operation, air is compressed by the low-pressure compressor and collected by a plurality of pipes and scrolls and then channeled through an intercooler that is coupled remotely from the gas turbine engine. The cooled air is then channeled back to the high-pressure compressor through another set of pipes and scrolls. The high-pressure turbine drives the high-pressure compressor through a shaft. The intermediate pressure turbine drives the low-pressure compressor through a second shaft and the power turbine drives a load, e.g. a generator, through a third shaft.
However, since the gas turbine engine includes three separate shafts, and also includes a plurality of pipes and scrolls to channel the compressed air from the low-pressure compressor to the intercooler and then back to the high-pressure compressor, the gas turbine engine is relatively complex, and therefore requires additional time and costs to manufacture.